1. Field of the Invention
The present invention relates to a method and apparatus for shredding annular objects, preferably the carcasses of discarded tires, into multiple uniformly shaped pieces. More specifically, the invention includes a novel multi-stage apparatus which automatically divides tire carcasses into two side wall sections and a tread section. The apparatus then further divides the wall and tread sections into relatively small, uniform pieces. The pieces so formed are suitable for a variety of purposes, including recycling.
2. Description of the Prior Art
Ever since Charles Goodyear perfected the sulphur vulcanization of rubber, tires for vehicles of every imaginable design have been made from rubber. However, as was quickly discovered, in order to fabricate a rubber tire having a suitably long operational lifetime, it is necessary to add a host of different additives to the rubber. For instance, carbon black is added in large amounts to rubber in order to impart durability and UV-light stability to the finished tire.
In the years during and immediately following World War II, the use of natural rubber for fabricating tires was largely abandoned, at first due to the war time unavailability of natural rubber and during the 1950's, because of the invention of various synthetic rubbers. However, even synthetic rubbers still must be extensively formulated with various additives in order to yield a commercially acceptable tire.
The last three decades have seen a steady improvement in the synthetic rubber art to the point that tires, automobile tires especially, are now extremely resistant to environmental degradation. This is very beneficial for tire consumers, but presents various persistent problems regarding the safe disposal or recycling of spent tire carcasses.
For instance, because of their annular shape, tires occupy a very large volume of landfill space, even though the actual volume of material which makes up each tire is very small. For this reason, many landfills located near crowded urban areas bar the disposal of tire carcasses because they occupy a disproportionately large volume of precious landfill space. Therefore, waste tire carcasses are often disposed of illegally, or must be transported to more remote landfills where space is not a a premium.
In fact, landfills composed entirely of tire carcasses are known, but are also known to present unacceptably high risks of spontaneous and uncontrollable fires. These fires, in turn, produce huge volumes of thick, noxious and poisonous gases. For instance, a recent fire at a tire dump in Canada burned with such ferocity and produced such a large amount of heat and smoke that the Canadian authorities had no choice but to allow the fire to burn itself out. Unfortunately, this took several months.
Therefore, rather than dispose of tire carcasses, many investigators have focused on recycling the rubber in tires. But because tires are relatively large and come in a great variety of sizes, they cannot be directly subjected to chemical or physical recycling, but must first be altered to yield a uniformly sized product. Therefore, the first step in recycling rubber tires is to shred the tires into small, substantially uniform pieces. The small pieces or "tabs", provide a starting material for recycling, in which the product is characterized by easy handling and a much smaller volume of storage space than the tires themselves. Even if recycling of the tires is not contemplated, shredding tires makes them far easier to store and transport. To that end, a number of tire cutting devices have been described in the patent literature.
For instance, U.S. Pat. No. 3,548,898, issued Dec. 22, 1970, to V. Napolitano, describes a chuck for clamping and inflating a tubeless tire on a rasping machine. The tire is securely clamped between two such chucks and inflated for the purpose of re-treading the tire. Each chuck includes multiple segmental elements having semi-circular surfaces which slidingly engage the bead of the tire workpiece and form a tight seal therewith. A plurality of air channels in communication with the segmental elements is provided to inflate the tire, once a complete seal is formed around the bead of the tire. Rotation of the chucks will then rotate the tire, which is centered between them. The segmental elements which form the seal to the tire bead are interchangeable, so that the apparatus is capable of accommodating tires having different internal diameters.
U.S. Pat. No. 3,701,296, issued Oct. 31, 1972, to J. Snow, describes an apparatus for cutting strips of resilient material from tire treads. The apparatus includes a roller for supporting and rotating a tire and a piston to lift the rotating tire into contact with a first cutting head. The cutting head severs an annular tread section from the tire. The annulus so formed is then removed from the roller and transversely severed by a second blade to yield an elongated strip of resilient tread material. This reference contemplates using the tire material as bumper guards for boat trailers and the like.
U.S. Pat. No. 3,733,941, issued May 22, 1973, to W. Geyer, Jr., describes a single station apparatus which cuts tires circumferentially into annular pieces. The device has a base portion onto which a tire is releasably fixed in a flat, horizontal position. A rotatable shaft, including a blade assembly is disposed within the inner diameter of the tire. The blade assembly is mounted on an adjustable boom which can be made to rotate by rotating the shaft. The boom is adjustable to urge the blade assembly against the outer surface of the tire. By adjusting the boom and rotating the shaft, the tire can be divided into multiple annular pieces. In this reference, it is the tire that remains stationary, while the blade moves about the circumference of the tire.
U.S. Pat. No. 3,830,120, issued Aug. 20, 1974, to H. Peterson, describes yet another tire cutting apparatus in which a tire work piece is mounted in a vertical position upon a hydraulically movable mandrel. The tire is then lifted by the mandrel to contact a stationary rotating blade, which cuts the tire circumferentially.
U.S. Pat. No. 4,096,772, issued Jun. 27, 1978, to W. Hall, et al., describes a vertical tire slitting apparatus which includes external guide means that contact the side walls of the tire being rendered. In contrast to the Peterson device, the cutting head of this apparatus fits inside the annulus of the tire and penetrates the inner surface of the tire, rather than the outer surface. The apparatus includes a frame, a cutter head which fits inside the tire workpiece and a tire drive mechanism attached to the frame to rotatably drive the tire about the cutter head, thereby slitting the tire into multiple annular pieces.
U.S. Pat. No. 4,338,839, issued Jul. 13, 1982, to Farrell, Sr. et al., describes an apparatus for cutting a waste tire into segmental pieces, rather then annular pieces. The apparatus includes a cutting head having multiple pairs of movable blades mounted on a hydraulic ram and several pairs of stationary blades mounted on a base. A tire workpiece is laid flat, below the cutting head and directly on top of the stationary blades and the ram is used to drive both the movable and stationary blades through the tire, thereby cutting the tire into multiple segments.
U.S. Pat. No. 4,694,716, issued Sep. 22, 1987, to T. Sakamoto, describes an apparatus similar to Farrell, Sr., et al., above, except that there is only one upper blade assembly, which is mounted on a rotatable shaft and driven by a hydraulic ram. Between the blade assembly and the tire workpiece is a presser plate having slits which are in registration with the blades of the blade assembly. The presser plate prevents pieces of the cut tire from becoming lodged in the voids between the individual cutting blades. In operation, a tire workpiece is placed horizontally below the cutting press and the presser plate is urged against the tire to compress it. The blade assembly is then lowered through the slits in the presser plate to cut the tire. The blade/presser plate assembly is then retracted and rotated slightly. The process can then be repeated to further render the tire.
U.S. Pat. No. 5,024,386, issued Jun. 18, 1991, to A. Morris, describes an apparatus which first de-beads a tire, and then cuts the tire workpiece diametrically to yield at least two U-shaped segments. The individual segments are then spread flat and fed into a shredder while held in the flattened position.
U.S. Pat. No. 5,147,163, issued Sep. 15, 1992, to Booker, et al., describes another vertical tire splitting device which includes an open-top box having adjustable floor members, into which a tire is placed in a vertical orientation. A mechanism is provided to firmly anchor and rotate the tire slightly more than one revolution, while contacting the tire with a cutting blade. The blade severs the bead or the tread of the tire from the tire carcass in one revolution of the tire. The adjustable floor members are then manipulated to move the slitted tire carcass from the box.
U.S. Pat. No. 5,199,337, issued Apr. 6, 1993, to J. Parker, describes a horizontal tire shredding apparatus in which the tire is supported on a horizontal, rotatable support and rotated by diametrically opposed drive means. Diametrically opposed cutting means are then contacted with the tire to cut it circumferentially.
U.S. Pat. No. 5,257,561, issued Nov. 2, 1993, to E. Folta, describes a locking chuck-type assembly for securely holding tires. The assembly has two disengageable halves which can be releasably engaged to one another with a tire securely clamped in between the two. The assembly is rotatable and once the tire is secured, the tire can be balanced, graded, ground and further processed.
U.S. Pat. No. 5,267,496, issued Dec. 7, 1993, to R. Roach, et al., describes a vertical tire cutting apparatus which radially cuts the tire using a star-like cutting head. The tire is first placed inside a vertical housing and clamped between twelve sets of jaws so that the two beads of the tire actually touch. A radially-arranged blade assembly having multiple blades in a vertical orientation is then driven through the compressed tire, thereby shredding it into several U-shaped pieces. The tire is never cut circumferentially.
The following patent references, both United States patents and patents granted by foreign nations, are believed to contain teachings which are cumulative to the above-discussed patents: U.S. Pat. No. 4,405,090, issued Sep. 20, 1983, to D. Wakeem; U.S. Pat. No. 3,674,067, issued Jul. 4, 1972, to D. Cooper; U.S. Pat. No. 125,699, issued Apr. 16, 1872, to I. Siegrist; U.S. Pat. No. 400,999, issued Apr. 9, 1889, to F. Bloomqvist; Japanese Patent No. 51-41775, issued April 1976; Japanese Patent No. 52-23785, issued February 1977; Japanese Patent No. 53-11999, issued April 1978; Japanese Patent No. 53-34235, issued September 1978; Soviet Union Certificate No. 1079283 A, issued March 1984; and Soviet Union Certificate No. 1684062 A1, issued October 1991.
It is an object of this invention to provide a new and improved tire shredding apparatus which separates the tread from the side walls of the tire and shreds both the tread and the side walls in separate cutting operations.
Another object of the invention is to provide an automated tire cutting or shredding apparatus which automatically sizes a tire, rotates the tire in the presence of a cutter blade, cuts the tire into three pieces to define a tread section and two side wall sections and subsequently cuts the side wall sections and, optionally the tread, into small pieces.
These and other objects of the invention are provided in:
An automated tire shredding apparatus which includes:
1. a releasable tire orienting and rotating mechanism for engaging and vertically orienting and rotating a tire;
2. a prime mover operationally connected to the releasable tire orienting and rotating means by power transmitting elements;
3. a movable cutter head, including at least two adjustable cutter head blades, the cutter head and cutter head blades movably engageable with the tire when the tire is rotated by the releasable tire orienting and rotating mechanism, the cutter head blades capable of cutting circumferentially through the tire;
4. two tire side wall conveyor means, having a floor, two walls, an inlet end and an outlet end, the inlet end dimensioned and configured to retain a tire side wall in a substantially vertical orientation and the outlet end dimensioned and configured to retain a tire side wall in a substantially horizontal orientation and the two walls gradually sloping to connect the inlet end to the outlet end;
5. two horizontally disposed radial blade assemblies, one of which is disposed adjacent to the outlet end of each of the side wall conveyors, respectively, each of the radial blade assemblies having multiple, radially disposed blades;
6. two press heads, one of which is operationally disposed adjacent to one of the radial blade assemblies and the other operationally disposed adjacent to the other of the radial blade assemblies, each of the press heads capable of reciprocating between a first position removed from the radial blade assemblies for receiving a tire side wall and a second position flush with the radial blade assemblies for radially cutting a tire side wall; and
7. a prime mover such as a motor and belt system operationally connected to the press heads, wherein the tire is circumferentially cut by the cutter head blades to define a tire tread and a pair of tire side walls and the tire side walls are transported by rotational momentum to the radial blade assemblies, where the tire side walls are radially cut into pieces responsive to operation of the radial blade assemblies, the radially-disposed blades and the press heads.
A method of shredding a tire having a main axis of rotation into multiple substantially uniformly-sized pieces, which includes the steps of;
1. orienting and releasably and rotatably fixing the tire such that the main axis of rotation is horizontal;
2. rotating the tire about the main axis of rotation;
3. contacting the rotating tire with a pair of cutting blades for circumferentially slitting the tire into a center tread section and right and left side wall sections, each of the right and left side wall sections rotating about the main axis of rotation, wherein the center tread section falls free of the right and left side wall sections and the center tread section is transported by its rotational momentum away from the right and left side wall sections;
4. releasing the right and left side wall sections, such that the right and left side wall sections are each transported by their rotational momentum to one of two radial cutting presses;
5. biasing each of the right and left side wall sections against a blade assembly, the blade assembly including multiple blades; and
6. radially cutting each of the right and left side wall sections into multiple substantially uniformly-sized pieces by operation of the blades.